Mine Ventilation Network Research Articles

An evaluation of a perfluoromethylcyclohexane (PMCH) permeation plug release vessel (PPRV) in a controlled turbulent environment

The use of sulfur hexafluoride (SF6) as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30years. As a result, the methods used to release, sample, and analyze SF6 are well accepted. As the complexity and size of underground mine ventilation networks increase, the ability of a SF6 to function as a convenient and rapid means of analysis diminishes. The utilization of multiple tracer gases can mitigate this by removing the need to purge the background presence of a tracer before conducting another release and allowing for a more comprehensive evaluation using multi-zone techniques. Recent studies have identified perfluoromethylcyclohexane (PMCH) as a possible supplement for SF6 in underground mine ventilation tracer studies. However, the deployment of PMCH remains a challenge because of this compounds physical properties. This paper evaluates a PMCH permeation plug release vessel (PPRV) under controlled turbulent conditions. The details of the experimental parameters used in the evaluation as well as a discussion regarding the performance of the PPRV are included.

Optimization of air quantity regulation in mine ventilation networks using the improved differential evolution algorithm and critical path method

In mine ventilation networks, the reasonable airflow distribution is very important for the production safety and economy. Three basic problems of the natural, full-controlled and semi-controlled splitting were reviewed in the paper. Aiming at the high difficulty semi-controlled splitting problem, the general nonlinear multi-objectives optimization mathematical model with constraints was established based on the theory of mine ventilation networks. A new algorithm, which combined the improved differential evaluation and the critical path method (CPM) based on the multivariable separate solution strategy, was put forward to search for the global optimal solution more efficiently. In each step of evolution, the feasible solutions of air quantity distribution are firstly produced by the improved differential evolution algorithm, and then the optimal solutions of regulator pressure drop are obtained by the CPM. Through finite steps iterations, the optimal solution can be given. In this new algorithm, the population of feasible solutions were sorted and grouped for enhancing the global search ability and the individuals in general group were randomly initialized for keeping diversity. Meanwhile, the individual neighborhood in the fine group which may be closely to the optimal solutions were searched locally and slightly for achieving a balance between global searching and local searching, thus improving the convergence rate. The computer program was developed based on this method. Finally, the two ventilation networks with single-fan and multi-fans were solved. The results show that this algorithm has advantages of high effectiveness, fast convergence, good robustness and flexibility. This computer program could be used to solve large-scale generalized ventilation networks optimization problem in the future.

Determining Diagonal Branches in Mine Ventilation Networks

Abstract The present paper discusses determining diagonal branches in a mine ventilation network by means of a method based on the relationship A⊗ PT(k, l) = M, which states that the nodal-branch incidence matrix A, modulo-2 multiplied by the transposed path matrix PT(k, l ) from node no. k to node no. l, yields the matrix M where all the elements in rows k and l - corresponding to the start and the end node - are 1, and where the elements in the remaining rows are 0, exclusively. If a row of the matrix M is to contain only „0” elements, the following condition has to be fulfilled: after multiplying the elements of a row of the matrix A by the elements of a column of the matrix PT(k, l), i.e. by the elements of a proper row of the matrix P(k, l ), the result row must display only „0” elements or an even number of „1” entries, as only such a number of „1” entries yields 0 when modulo-2 added - and since the rows of the matrix A correspond to the graph nodes, and the path nodes level is 2 (apart from the nodes k and l, whose level is 1), then the number of „1” elements in a row has to be 0 or 2. If, in turn, the rows k and l of the matrix M are to contain only „1” elements, the following condition has to be fulfilled: after multiplying the elements of the row k or l of the matrix A by the elements of a column of the matrix PT(k, l), the result row must display an uneven number of „1” entries, as only such a number of „1” entries yields 1 when modulo-2 added - and since the rows of the matrix A correspond to the graph nodes, and the level of the i and j path nodes is 1, then the number of „1” elements in a row has to be 1. The process of determining diagonal branches by means of this method was demonstrated using the example of a simple ventilation network with two upcast shafts and one downcast shaft.

Researches and applications on geostatistical simulation and laboratory modeling of mine ventilation network and gas drainage zone

The mine disaster of gas at working face and goaf creates a risky working environment for miners, and causes a mass of casualties in mining industry around the world. The key points of resolving the gas problem are to properly increase fresh air volume in ventilation network, exactly determining the gas emission zone, and implementing a reasonable gas drainage plan. This article provides multiple gas control methods with the aim of improving the gas drainage knowledge and techniques. Both of the CFD model and the mini mine gas emission zone based on U+L type ventilation network are established, and the gas distribution and movement rules of working face and goaf are accurately obtained during the numerical and laboratorial simulation experiments are performed. The results reveal that gas problems at working face and goaf cannot be effectively resolved by only increasing the air volume; instead, it must be combined with optimizing the ventilation network and excavating special gas drainage tunnels. The experimental results also demonstrate that the most effective gas extraction spot constantly varies with the zone where mining activities are performed. Therefore, the arrangement of gas drainage tunnels is determined according to the obtained rules and experimental results. The field verification results show that the layout of the drilling boreholes is rational and effective; the gas drainage quantity is reliable and stable, which indicates that it is valid and feasible to arrange the layout of gas drilling tunnels based on the combination experimental results of numerical simulations and laboratory tests.

SIMULATION MODELING OF NEURAL CONTROL SYSTEM FOR SECTION OF MINE VENTILATION NETWORK

Static and dynamic simulation models of a section of a mine ventilation network in order to research a sequential neural control scheme of mine airflow are developed in this paper. The techniques of neural network training set creation for both simulation models, a structure of neural network and its training algorithm are described. The simulation modeling results using static and dynamic models have showed good potential capabilities of neural control approach.

NEURAL-NETWORK BASED METHOD OF CONTROL INFLUENCES FORMING IN COMPUTER SYSTEM CONTROLLING ENVIRONMENTAL PARAMETERS

A simulation model of a section of mine ventilation network is considered in this paper. The simulation modeling of transient aerogasdynamic processes of methane concentration changing is fulfilled at applying position and exponential control influences. There is proposed a neural-based method of control influences forming by neural network training on the set of optimal control influences. There are defined a criterion and developed an algorithm of optimal control influences forming as a training set of neural network. The simulation modeling of applying of control influences formed by neural network is fulfilled and decreasing of control parameter in the section of mine ventilation network is estimated.

Optimisation of mine ventilation networks using the Lagrangian algorithm for equality constraints

This work presents a new method of mine ventilation network optimisation as standard non-linear programming problem and discusses the use of a novel first-order Lagrangian (FOL) algorithm for equality constraints as a solution tool for these problems. Slack variables have been defined to transform such inequality constraints into their corresponding equality forms. The problem is then converted to non-linear problem with equality constrains. The methodology adopted in this paper is capable of dealing with the non-linear convex model with significant savings on computational efforts due to its use of only first derivatives. A MATLAB programme has been developed based on the FOL method to solve a generalised mine ventilation network optimisation problem. To study the validity and the viability of the FOL programme, the programme has been applied to already published network problems and both results are identical.

The Airflow Abnormal Value Analysis of Mine Ventilation Network Based on the Sensitivity

Based on the analysis of network theory and the airflow abnormal value of mine ventilation, the concept of sensitivity was introduced and a mathematical model to analyze the reason for the airflow abnormal values so as to realize the analysis for the airflow in all kinds of tunnels of ventilation system was put forward. By doing that, various reasons for the airflow abnormal value could be found so that possible predictions for the safety consequences could be made accordingly.

Classification of Structural Complexity for Mine Ventilation Networks

The mine ventilation system is most important and technical measure for ensuring safety production in mines. The structural complexity of a mine ventilation network can directly affect the safety and reliability of the underground mining system. Quantitatively justifying the degree of complexity can contribute to providing a deeper understanding of the essential characteristics of a network. However, so far, there is no such a model which is able to simply, practically, reasonably, and quantitatively determine or compare the structural complexity of different ventilation networks. In this article, by analyzing some typical parameters of a mine ventilation network, we conclude that there is a linear functional relationship among five key parameters (number of ventilation network branches, number of nodes, number of independent circuits, number of independent paths, and number of diagonal branches). Correlation analyses for the main parameters of ventilation networks are conducted based on SPSS. Based on these findings, a new evaluation model for the structural complexity of ventilation network (which is represented by C) has been proposed. By combining SPSS classification analyses results with the characteristics of mine ventilation networks, standards for the complexity classification of mine ventilation systems are put forward. Using the developed model, we carried out analyses and comparisons for the structural complexity of ventilation networks for typical mines. Case demonstrations show that the classification results correspond to the actual situations. © 2014 Wiley Periodicals, Inc. Complexity 21: 21–34, 2015

Assessment of air dispersion characteristic in underground mine ventilation: Field measurement and numerical evaluation

The environmental safety of an underground mine depends strongly on its ventilation system. An efficient ventilation system provides fresh air, removes hazardous gases and dust, and maintains the temperature and humidity at appropriate levels. One of the most important factors in removing hazardous gases and dust is the dispersion behaviour in the mine network. This factor determines the longitudinal spreading and the average air residence time of gases or particulate matter throughout the mine. This paper describes tracer gas measurement in an underground mine and the utilisation and analysis of the dispersion characteristics using numerical simulations. The concentration–time curve obtained from the measurement is simulated to evaluate the effective diffusion coefficient that reflects the general dispersion characteristic of an entire mine. The evaluated values of effective diffusion coefficient are then compared to other data from several studies. The diffusivities obtained in this study were higher than other analytical and empirical results. More research is still required to identify the main factors causing such higher diffusivities. However, the results from the present work can be an important standpoint for future work. Numerical simulation conducted in this research was confirmed to be effective in detecting several leakage paths occurring in the mine ventilation network.

Reliability Calculation of Mine Ventilation Network

A good ventilation system should reflect both safety reliable and economical reasonable. Safe and reliable mine ventilation system have high reliability and resilience during normal operation or in the disaster period. There is a close relationship between the reliability of mine ventilation network and the reliability of network branch. In order to make quantitative evaluation to the reliability of mine ventilation network. Based on the mine ventilation network equilibrium law, reliability theory is applied to the calculation of the branch of ventilation network, disjoint Boolean algebra is used to calculate the reliability of the network. This method has the advantages of simple operation, small calculation error etc.It will be helpful to the design, management and technological transformation of mine ventilation network.

COMPUTERIZED SIMULATION OF MINE VENTILATION NETWORKS FOR SUSTAINABLE DECISION MAKING PROCESS

The simulation of different situations that may occur in the operation of the mine ventilation network is performed on its virtual model, developed and optimized using dedicated software. Depending on the chosen scenario, on the network model are applied a number of changes (addition of new ventilation workings, addition / removal of branches and nodes, changes in aerodynamic parameters: pressure, air flow driven by the fan etc.), the ultimate goals being: to assess how the new model obtained respond to anticipated requirements, diagnose of existing or potential problems, providing a quick feedback to the operator by making available all the data necessary for decision making process. The complexity of the simulation lies in the need to execute a number of operations due to changes of the network structure and symbolism carried out on the virtual model. This article aims to simplify this process through automation and efficiency using software subroutines, subroutines containing the entire chain of operations performed for each step of the simulation, in order to reduce the simulation time and the level of complexity required for understanding the phenomena that occur in the mine ventilation networks.

Shock losses characterization of ventilation circuits for block caving production levels

With the tendency of world ore deposits to be deeper and of lower grade, block caving is becoming an increasingly important mining method. As with any underground method, an adequate mine ventilation system is essential to control operational costs while achieving the development and production schedule. This paper presents results obtained from a simulation based on Computational Fluid Dynamics (CFD), in combination with a mine ventilation network solver, to determine the head losses for the ventilation circuits of the production level drifts within the block caving layout at the El Teniente mine. In order to simulate the ventilation network, the airflow path is characterized in terms of shock losses from the intake ventilation sublevel through the drifts to the exhaust ventilation sublevel. Subsequently, these simulated head losses are used for the ventilation model of the drift and solved using a commercial ventilation program, to assess the energy loss. Simple energy saving modifications can then be proposed, generating 25% savings. This methodology assists in the design of production levels having efficient mine ventilation systems.

Ventilation Optimization for Multi-Level Mining Based on Global Ventilation Network Simulation

Multi-level mining caused confusion of air return of overall ventilation system in Jinshandian Iron Mine. Based on fluid simulation software ANSYS-CFX, a modeling method of replacing fans with negative pressure section was proposed to build accurate 3D global model of mine ventilation network. Four feasible ventilation network optimization schemes were proposed. Airflow speed of inlet and air pressure of outlet was simulated in each scheme. To the principle of minimum ventilation energy, the scheme of return air through out3 and-270m level was determined as the optimal scheme. Using orthogonal experiment, three factors and three levels of variance analysis of airflow speed in each return air shaft was carried on. The functions of negative pressure of fans to airflow speed of outlet was built to calculate the optimal negative pressure parameter of each fan, which could realize the optimal allocation of air quantity and pressure in ventilation system.

Application of Fuzzy Mathematics in Selection Air Flow Regulating Program

Selecting the optimal air regulation scheme of mine ventilation network, the essence is to choose the network a most optimal tree and obtain the corresponding optimal cosine tree combination program.Due to a synthetic consideration of the influence of production.Management economy and other aspects on the tree selection,the air flow regulating and controlling system made by the authors is optimum It is satisfactory to use the model for the north part ventilation system of Laochang tin mine of Yunnan tin Industrial crop. It is of practical significance to combine organically air flow regulating and controlling system with mine ventilation system.

Application of Fuzzy Mathematics in the Networks Optimization of Mine Ventilation System

The metal mine ventilation system is a complex system composed of interactive factors. To get a relative impersonal assessment result of the metal mine ventilation system, the issues, network optimization and program optimization, were discussed and the fuzzy optimization of metal min ventilation system was presented in this paper. Based on the two classic nonlinear programming models for mine ventilation networks, the mathematical model of fuzzy optimization for mine ventilation networks was put forward. A algorithm principle is provided for solving the superior support in a quicker and easier way.

Database Design of Three Dimensional Simulation and Optimization System for Mine Ventilation Network

According to the characteristic of three dimensional simulation system for mine ventilation and database technology situation, the systems database was built by SQL Server. This paper analysed the data model, data dictionary, database access control strategy and technology, which provided solid dependence for the stable operation of the simulation system.

Stability of multiple fans in mine ventilation networks

In large mines, single fan is usually not enough to ventilate all the working areas. Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantities associated with each fan in the network. Accordingly, each fan in a multiple-fan system has its own mine characteristic curve, or a subsystem curve. Under some consideration, the conventional concept of a mine characteristic curve of a single-fan system can be directly extended to that of a particular fan within a multiple-fan system. In this paper the mutual effect of the fans on each other and their effect on the stability of the ventilation network were investigated by Hardy Cross algorithm combined with a switching-parameters technique. To show the validity and reliability of this algorithm, the stability of the ventilation system of Abu-Tartur Mine (one of the largest underground mine in Egypt) has been studied.

Dynamic Analytical Platform for Mine Ventilation Networks

Mine disasters frequently occur with serious consequences, so additional research is needed to effectively deal with mine disasters especially the secondary catastrophes. Modularization modeling method was used to develop the dynamic analytical platform for modeling mine ventilation networks. The platform includes models of the ventilation network and the control systems. A small experimental ventilation network was also constructed to validate the platform. The results show that the platform provides accurate real-time simulations of normal operations and accident conditions in the ventilation network. The platform accurately models dynamic spreading of the disaster in the lab with errors of around 5%. Thus, the platform can be used to analyze the mine ventilation systems during accidents and develop methods to prevent the secondary catastrophes and the deterioration of mine disasters.

Procedure of joint calculation of temperature and ventilation mode in uninterrupted mining in permafrost zone

The authors have developed a procedure for forecasting air flow, air and rock temperatures as well as thawing halo in all roadways of a mine, taking into account stage-wise introduction of new mine workings into the mine ventilation network, or backfilling of the mined-out stopes.